Remote Administration tools

[foragersec () yahoo co in]

Plz suggest some good remote administration tools with following criteria :
1] Preferable Free / Opensource
2] Should work on both Windows & Mac, ( if works on linux as well, great! )
3] Should have some auditable password control
4] Hasslefree when connecting to remote offices/workstations
5] Performance - good to have
 
Tools already being considered :
1] GotoAssist from http://www.citrixonline.com/
2] VNC ( Issues as does not have central password control
3] Radmin3

Thanks and Regards,